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notcurses/src/lib/metric.c

119 lines
3.6 KiB
C

#include <fenv.h>
#include <string.h>
#include <locale.h>
#include <pthread.h>
#include <inttypes.h>
#include "notcurses/notcurses.h"
#include "internal.h"
static const wchar_t UTF8_SUBPREFIX[] = L"mµnpfazy"; // 10^24-1
static const wchar_t ASCII_SUBPREFIX[] = L"munpfazy"; // 10^24-1
static const wchar_t* SUBPREFIXES = ASCII_SUBPREFIX;
static pthread_once_t utf8_detector = PTHREAD_ONCE_INIT;
// sure hope we've called setlocale() by the time we hit this!
static void
detect_utf8(void){
const char* encoding = nl_langinfo(CODESET);
if(encoding){
if(strcmp(encoding, "UTF-8") == 0){
SUBPREFIXES = UTF8_SUBPREFIX;
}
}
}
const char* ncnmetric(uintmax_t val, size_t s, uintmax_t decimal,
char* buf, int omitdec, uintmax_t mult,
int uprefix){
// FIXME this is global to the process...ick :/
fesetround(FE_TONEAREST);
pthread_once(&utf8_detector, detect_utf8);
// these two must have the same number of elements
const wchar_t* subprefixes = SUBPREFIXES;
const wchar_t prefixes[] = L"KMGTPEZY"; // 10^21-1 encompasses 2^64-1
if(decimal == 0 || mult == 0){
return NULL;
}
if(decimal > UINTMAX_MAX / 10){
return NULL;
}
unsigned consumed = 0;
uintmax_t dv = mult;
if(decimal <= val || val == 0){
// FIXME verify that input < 2^89, wish we had static_assert() :/
while((val / decimal) >= dv && consumed < sizeof(prefixes) / sizeof(*prefixes)){
dv *= mult;
++consumed;
if(UINTMAX_MAX / dv < mult){ // near overflow--can't scale dv again
break;
}
}
}else{
while(val < decimal && consumed < sizeof(prefixes) / sizeof(*prefixes)){
val *= mult;
++consumed;
if(UINTMAX_MAX / dv < mult){ // near overflow--can't scale dv again
break;
}
}
}
int sprintfed;
if(dv != mult){ // if consumed == 0, dv must equal mult
if((val / decimal) / dv > 0){
++consumed;
}else{
dv /= mult;
}
val /= decimal;
// Remainder is val % dv, but we want a percentage as scaled integer.
// Ideally we would multiply by 100 and divide the result by dv, for
// maximum accuracy (dv might not be a multiple of 10--it is not for
// 1,024). That can overflow with large 64-bit values, but we can first
// divide both sides by mult, and then scale by 100.
if(omitdec && (val % dv) == 0){
sprintfed = snprintf(buf, s, "%" PRIu64 "%lc", (uint64_t)(val / dv),
(wint_t)prefixes[consumed - 1]);
}else{
sprintfed = snprintf(buf, s, "%.2f%lc", (double)val / dv,
(wint_t)prefixes[consumed - 1]);
}
if(sprintfed < 0){
return NULL;
}
if(uprefix){
if((size_t)sprintfed < s){
buf[sprintfed] = uprefix;
buf[++sprintfed] = '\0';
}
}
return buf;
}
// unscaled output, consumed == 0, dv == mult
// val / decimal < dv (or we ran out of prefixes)
if(omitdec && val % decimal == 0){
if(consumed){
sprintfed = snprintf(buf, s, "%" PRIu64 "%lc", (uint64_t)(val / decimal),
(wint_t)subprefixes[consumed - 1]);
}else{
sprintfed = snprintf(buf, s, "%" PRIu64, (uint64_t)(val / decimal));
}
}else{
if(consumed){
sprintfed = snprintf(buf, s, "%.2f%lc", (double)val / decimal,
(wint_t)subprefixes[consumed - 1]);
}else{
sprintfed = snprintf(buf, s, "%.2f", (double)val / decimal);
}
}
if(sprintfed < 0){
return NULL;
}
if(consumed && uprefix){
if((size_t)sprintfed < s){
buf[sprintfed] = uprefix;
buf[++sprintfed] = '\0';
}
}
return buf;
}